I'm wondering if I need to buy a jabot specifically, or just tie a cravat in the right way to get his... ruffles (for lack of a better word) to look right?

You might find someone hocking a jabot under the term "cravat". These fashion terms seem to be sort of tossed around pretty loosely in the marketplace. (Don't get me started on "ruching"...) Basically you just want to make sure that you have three layers of fabric showing. A cravat can technically only give you two, as it is formed by wrapping a single length of fabric around one's neck like these. No matter how you tie it or what the ends look like, you'll only get two layers.

Hmmm... unless of course you were to sew an extra piece to one of the ends to make it look like three layers. Hah. Actually that could probably work.

But then at that point, you're trying to match fabric to something pre-bought which can be difficult and time-consuming, so you might want to just make it from scratch ^^;. And at THAT point, the jabbot is actually easier to make. It's just three tiers of ruffled fabric that you pin to a collar. If you make a cravat you'd have to figure out how long it has to be to wrap around your neck to get the end-length to be how you want it, etc.

...that may be more info than you needed, but hey! Knowing is half the battle lol.